1. Field of the Invention
The present invention relates to surgical instruments for applying surgical fasteners or staples to body tissue, and more particularly to an apparatus for applying surgical fasteners having adjustable mechanisms for controlling the spacing between the jaw members through which the tissue passes during the fastening or stapling procedures.
2. Discussion of the Related Art
Surgical fastening devices having means for controlling the spacing between the jaw members are well known in the art. These devices typically include indicating means to provide a reading of the spacing between the jaw members. Devices are also known in the an which provide latching mechanisms to actuate the firing mechanism only when the distance between the jaws is within a preset range. These devices typically include a complex lock-out mechanism.
Various closing mechanisms are provided in the prior art for use with surgical fastening devices. The most notable of these devices utilize a complex worm gear-type arrangement or screw bearing member to open and close the spacing between the jaw members of the surgical fastening apparatus. These devices generally provide a rotatable knob or wing-like assembly at the trigger end of the device remote from the jaw mechanism which carries the fastener cartridge, and a screw-like mechanism is provided that passes through the body of the device to translate the rotational movement of the knob into longitudinal movement of the cartridge frame to open and close the spacing between the jaws. As the jaw members are closed around a tissue site to which fasteners are to be applied, the surgeon must grasp the device with one hand while rotating the knob or wing-like assembly with the other hand. As the jaws members close about the tissue to pinch the tissue therebetween, the surgeon then ceases rotation and activates the trigger mechanism to drive the fasteners into the tissue. Several known devices provide a trigger-like mechanism, while others provide a secondary rotatable knob for driving the fasteners by rotational movement. Many devices provide an indicator means near the rotatable knob which gives a visual indication of the spacing between the jaw members prior to firing.
These prior art devices are subject to several disadvantages in both use and construction which render these devices difficult to operate and expensive to manufacture. Many of the devices are cumbersome in use in that the surgeon must operate the device with both hands, holding the body of the instrument in one hand while rotating the knob or wing assembly with the other hand. This may lead to inaccurate stapling or fastening since the surgeon is unable to guide the tissue to be stapled or fastened with his free hand while closing the jaws about the tissue. Furthermore, the number of interacting components provides inaccuracies due to normal break down of tolerances. In addition, the gear arrangement may become worn during extended use, thus rendering an imprecise grasping action at the jaws.
Furthermore, these prior art devices generally involve a complex construction in which a precisely machined or cast worm gear must be constructed and incorporated into the device. This of course increases the cost of manufacturing, and requires a sophisticated assembly procedure to properly locate the worm gear in the instrument to control the spacing between the jaws.
Typical devices having a rotatable knob at the end portion adjacent the handle mechanism of the surgical stapling or fastening device are disclosed in, among others, U.S. Pat. No. 4,930,503 to Pruitt, U.S. Pat. No. 4,788,978 to Strekopytov et al., and U.S. Pat. No. 4,606,344 to DiGiovanni. In each of these devices, an elongated rod member having screw threads machined thereon is provided, which connects a rotatable knob positioned adjacent the handle members to a pusher mechanism which urges a movable jaw in a forward direction toward a stationary jaw to close the spacing between the jaw members. When a desired spacing is reached, a trigger mechanism may be activated to fire the fasteners through the tissue into the anvil member mounted on the stationary jaw. To remove the fastening instrument after application of the fasteners, the knob is rotated in an opposite direction which turns the screw threaded rod member to move the movable jaw member away from the stationary jaw member so that the entire device maybe removed from the tissue.
Surgical fastening instruments having a wing like arrangement positioned adjacent the handle assembly of a device for moving a movable jaw toward a stationary jaw for affixing surgical fasteners to tissue are disclosed in U.S. Pat. No. 4,442,964 to Becht, U.S. Pat. No. 4,354,628 to Green, and U.S. Pat. No. 3,795,034 to Strekopytov et al. These devices are similar to those described above except for the provision of a rotatable wing member in place of the rotatable knob. These devices are also provided with a screw threaded rod member which, when rotated, urges a movable jaw towards a stationary jaw to close the jaw members around tissue to be fastened together. After the application of surgical fasteners, the wing assembly is rotated in an opposite direction to draw the movable jaw away from the stationary jaw so that the instrument maybe removed from the tissue.
Surgical stapling of fastening instruments having a pivotable mechanism external to the device for moving a movable jaw toward a stationary jaw prior to affixing surgical fasteners to tissue are disclosed in, among others, U.S. Pat. No. 3,269,630 to Fleischer, U.S. Pat. No. 4,530,453 to Green, U.S. Pat. No. 4,715,520 to Roehr, Jr. et al., and U.S. Pat. No. 4,978,049 to Green.
Green ('453), Roehr, Jr. et al. and Green ('049) each disclose a pivotable lever member which urges a movable jaw into proximity of a stationary jaw prior to application of the surgical fasteners. Fleischer discloses a surgical stapling instrument in which a pivotable handle urges the movable staple cartridge against the tissue in the direction of the stationary jaw and fires the staples in the same motion. In each of these devices, removal of the instrument after firing of the surgical fasteners is accomplished by pivoting the lever mechanism in the opposite direction to open the jaw members by moving the movable jaw away from the stationary jaw.
U.S. Pat. No. 5,190,203 to Rodak discloses a spring biased pivotal catch member for approximating the jaws which is held in selected positions by a pointed lance member.
The novel surgical stapling or surgical fastening device of the present invention obviates the disadvantages encountered in the prior art and provides an efficient surgical fastening device having an adjustable closure mechanism for controlling the spacing between the jaw members of the surgical fastening apparatus. The device of the present invention allows a surgeon to operate a surgical fastener with one hand while freeing the other hand to assist in the surgical procedure. Furthermore, the present invention provides a novel means for coupling the fastener driving mechanism to the firing mechanism when the jaws are approximated to a preset distance. The device of the present invention is of lightweight construction and provides ease of handling through the provision of a thumb controlled adjustable closure mechanism which permits a surgeon to set the spacing between the jaw members and fire the device while using only one hand.